Magnetic head apparatus having multiple recessed magnetic metal films

ABSTRACT

A slider being made of ferrite and a core formed with a magnetic metal film on its gap confronting surface are connected together by means of bonding glass so as to sandwich a non-magnetic film therebetween as a magnetic gap. The magnetic metal film is made of a magnetic metal material such as Fe--Ni, Fe--Al--Si and the like, and is constructed through the thin-film fabrication technology such as sputtering. A recessed portion is provided on the magnetic metal film in such a manner that the recessed portion is retracted from a medium confronting surface of the magnetic head by a depth t. Thus, no color change is caused on the magnetic metal material and, therefore, no deterioration in various characteristics of the magnetic head is expected.

This application is a division of now allowed application Ser. No.08/330,237 filed Oct. 27, 1994, which is a continuation of applicationSer. No. 07/983,027, filed Nov. 30, 1992, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic head which is chiefly usedfor magnetically recording, reproducing, or erasing information in amagnetic disk device and the like.

2. Description of the Related Art

A typical magnetic head apparatus is perspectively shown in FIG. 14. InFIG. 14, a slider 1 is made of a magnetic oxide material such asferrite. This slider 1 has a pair of floating rails 2, 3 elongated inparallel with each other at opposite both ends of the slider 1. The flatsurfaces of these floating rails 2, 3 are confronted to a mediumsurface; e.g. a disk surface, so that the slider 1 can slide on themedium surface smoothly. Though illustrated up side down in FIG. 14,this slider 1 is to be placed on the medium so that these floating rails2, 3 are directly brought into contact with the medium surface.

The slider 1 further includes a center rail 4 having a predeterminedtrack width TW, provided between the floating rails 2 and 3 in parallelwith them. At one end of the slider 1, a C-shaped core 5 made ofmagnetic oxide material such as ferrite is provided in confrontingrelationship with the corresponding side edge of the center rail 4.

There is further provided a magnetic gap 9 through which the core 5 isfaced to the edge surface of the center rail 4. And also, a bondingglass 6 is provided to securely connect the core 5 to the slider 1. Awinding 7 is wound around a centrally extending vertical column portionof the core 5.

Details of the joint structure between the slider 1 and the core 5 isenlargedly shown in FIG. 15. As is apparent from FIG. 15, a magneticmetal film 8 is constructed on a surface 5a of the core is that isconfronted to the magnetic gap 9. This magnetic metal film 8 is made ofa magnetic metal material such as Fe--Ni or Fe--Al--Si and the like, andis constructed on the confronting surface 5a through an application ofthe thin film fabrication technology such as sputtering. The magneticgap 9 is a non-magnetic film made of a non-magnetic material such asSiO₂. This non-magnetic film 9 is constructed on the edge surface of theslider 1 through an application of the thin film fabrication technologysuch as sputtering.

An operation of the magnetic head apparatus constituted as describedabove is explained hereinafter with reference to FIGS. 18 and 17.

In FIGS. 18 and 17, reference numerals 10, 11, and 12 denote a magnetichead shown in FIG. 14, a magnetic disk, and air stream, respectively.When the magnetic disk 11 is not turned, the magnetic head 10 is laid onthe magnetic disk 11 stationarily in such a manner that the floatingrails 2, 3 and the center rail 4 are directly brought into contact withthe upper surface of the magnetic disk 11, as shown in FIG. 18. To thecontrary, once the magnetic disk 11 causes its turning movement, themagnetic head 10 comes to slide on the magnetic disk 11 with africtional engagement. If the rotational speed of the magnetic disk 11exceeds a predetermined value, the air stream 12 caused in relation tothe turning surface of the magnetic disk 11 becomes so strong that themagnetic head 10 takes off the magnetic disk 11 and keeps flying againstthe magnetic disk 11 by maintaining a certain gap.

However, such a conventional structure has the following problem. As themagnetic head 10 is directly contacted with the upper surface of themagnetic disk 11 in the case where the magnetic disk 11 is not turned,the magnetic metal film 8 is brought into contact with the magnetic disk11 at its confronting edge 8a. As enlargedly shown in FIG. 15(a), thesurface of magnetic disk 11 is usually coated by lubricant 100 and maybe wetted by moisture 101. If the magnetic metal film 8 made of activemetal is exposed in such a severe condition, the magnetic metal film 8may cause chemical reaction to generate color change which results indeterioration in various characteristics of the magnetic head.

SUMMARY OF THE INVENTION

Accordingly, the present invention has a purpose, in view ofabove-described problems or disadvantages, to provide a magnetic headthat does not cause any color change through the chemical reaction bythe magnetic metal film and the lubricant or moisture, thereby realizinga magnetic head apparatus which is capable of maintaining itscharacteristics nicely against lubricant and moisture.

In order to accomplish above purposes, a first aspect of the presentinvention provides a magnetic head apparatus comprising: a magneticmaterial constituting a magnetic circuit in a magnetic head; a magneticgap being provided at a part of said magnetic circuit; a magnetic metalmaterial constituting at least a part of said magnetic materialconstituting the magnetic circuit; a medium confronting surface beingmade on one side of said magnetic head so as to be brought into slidablecontact with a surface of a medium; said magnetic metal material havinga surface confronting at least partially to the surface of said medium;and said surface of the magnetic metal material being recessed away fromsaid medium confronting surface.

In a preferable mode of the first aspect of the present invention, therecessed surface of the magnetic metal material is retracted from themedium confronting surface by 2 nm to 20 nm.

A second aspect of the present invention provides a magnetic headapparatus comprising: a pair of cores constituting a part of a magnetichead; a winding groove provided at least on either of said cores; amagnetic gap provided between said pair of cores so as to be sandwichedtherebetween; a magnetic metal film being formed on a surface of atleast either of said cores, said surface facing toward said magneticgap; a medium confronting surface being made on one side of saidmagnetic head so as to be brought into slidable contact with a surfaceof a medium; said magnetic metal film having a surface confronting atleast partially to the surface of said medium; and said surface of themagnetic metal film being recessed away from said medium confrontingsurface.

In a preferable mode of the second aspect of the present invention, saidrecessed surface of the magnetic metal film is retracted from the mediumconfronting surface by 2 nm to 20 nm. And, said core is made of ferriteand said magnetic metal film is made of at least one material belongingto a group consisting of Fe--Ni series alloy, Fe--Al--Si series alloy,Fe series amorphous, and Co series amorphous.

Furthermore, a third aspect of the present invention provides a magnetichead apparatus comprising: a substrate constituting a pair of coreassemblies for a magnetic head; a laminated core provided on saidsubstrate, said laminated core being constituted by alternatelylaminating a magnetic metal film and an insulation film; a windinggroove provided on at least either of said core assemblies; a magneticgap provided between said pair of core assemblies so as to be sandwichedtherebetween; a medium confronting surface being made on one side ofsaid substrate so as to be brought into slidable contact with a surfaceof a medium; said magnetic metal film having a surface confronting atleast partially to the surface of said medium; and said surface of themagnetic metal film being recessed away from said medium confrontingsurface.

In a preferable mode of the third aspect of the present invention, saidrecessed surface of the magnetic metal film is retracted from the mediumconfronting surface by 2 nm to 20 nm. And, said insulation film is madeof SiO₂ and said magnetic metal film is made of at least one materialbelonging to a group consisting of Fe--Ni series alloy, Fe--Al--Siseries alloy, Fe series amorphous, and Co series amorphous.

Furthermore, a fourth aspect of the present invention provides amagnetic head apparatus comprising: a substrate constituting a part of amagnetic head; a pair of magnetic layers laminated through a magneticgap on the substrate; a coil layer provided between said pair ofmagnetic layers; a medium confronting surface being made on one side ofsaid substrate so as to be brought into slidable contact with a surfaceof a medium; said magnetic layer having a surface confronting at leastpartially to the surface of said medium; and said surface of themagnetic layer being recessed away from said medium confronting surface.

In a preferable mode of the fourth aspect of the present invention, saidrecessed surface of the magnetic layer is retracted from the mediumconfronting surface by 2 nm to 20 nm. And, at least either of saidmagnetic layers is made of at least one material belonging to a groupconsisting of Fe--Ni series alloy, Fe--Al--Si series alloy, Fe seriesamorphous, and Co series amorphous.

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription which is to be read in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a magnetic head apparatus inaccordance with a first embodiment of the present invention;

FIG. 2 is a fragmentally enlarged side view showing the magnetic headapparatus in accordance with the first embodiment of the presentinvention;

FIG. 2(a) is also a fragmentally enlarged side view showing the magnetichead apparatus in accordance with the first embodiment of the presentinvention;

FIG. 3 is a graph showing a relative output of the magnetic head inrelation to a recess depth of a magnetic metal film in accordance withthe first embodiment;

FIG. 4 is a perspective view showing a magnetic head apparatus inaccordance with a second embodiment of the present invention;

FIG. 5 is a fragmentally enlarged view showing the magnetic headapparatus in accordance with the second embodiment of the presentinvention.

FIG. 6 is a fragmentally enlarged cross-sectional view showing themagnetic head apparatus in accordance with the second embodiment of thepresent invention;

FIG. 7 is a graph showing a relative output of the magnetic head inrelation to a recess depth of a magnetic metal film in accordance withthe second embodiment;

FIG. 8 is a fragmentally enlarged cross-sectional view showing amodified magnetic head apparatus in accordance with the secondembodiment of the present invention;

FIG. 9 is a perspective view showing a magnetic head apparatus inaccordance with a third embodiment of the present invention;

FIG. 10 is a fragmentally enlarged plane view showing the magnetic headapparatus in accordance with the third embodiment of the presentinvention;

FIG. 11 is a fragmentally enlarged cross-sectional view showing themagnetic head apparatus in accordance with the third embodiment of thepresent invention;

FIG. 12 is a graph showing a relative output of the magnetic head inrelation to a recess depth of an upper magnetic layer and a lowermagnetic layer;

FIG. 13 is a side view showing a magnetic head apparatus in accordancewith a fourth embodiment of the present invention;

FIG. 14 is a perspective view showing a typical magnetic head apparatus;

FIG. 15 is a fragmentally enlarged side view showing the typicalmagnetic head apparatus;

FIG. 15(a) is also a fragmentally enlarged side view showing the typicalmagnetic head apparatus;

FIG. 16 is a side view illustrating a stationary condition of thetypical magnetic head laid on the magnetic disk; and,

FIG. 17 is a side view illustrating a dynamic condition of the typicalmagnetic head flying above the magnetic disk.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, with reference to accompanying drawings, preferredembodiments of the present invention are explained in detail. As thefundamental function and operation of the magnetic head and the magneticdisk in each embodiment are the same as those of above-described typicalmagnetic head apparatus, it should be noted that the above-describedexplanation regarding such a fundamental affair is directly applied tothe later described explanation of each embodiment of the presentinvention.

FIRST EMBODIMENT

A magnetic head apparatus in accordance with a first embodiment of thepresent invention is perspectively shown in FIG. 1. The magnetic headapparatus shown in FIG. 1 is illustrated as an example obtained bysimply applying the present invention to the typical magnetic headapparatus described with reference to FIG. 14.

In FIG. 1, a slider 1 is made of magnetic oxide material such asferrite. This slider 1 has a pair of floating rails 2, 3 elongated inparallel with each other at opposite both ends of the slider 1. The flatsurfaces of these floating rails 2, 3 are confronted to a media surface;e.g. a disk surface. Though illustrated up side down in FIG. 1, thisslider 1 is to be placed on the medium so that these floating rails 2, 3are directly brought into contact with the medium surface.

The slider 1 further includes a center rail 4 having a predeterminedtrack width TW, provided between the floating rails 2 and 3 in parallelwith them. At one end of the slider 1, a C-shaped core 5 made ofmagnetic oxide material such as ferrite is provided in confrontingrelationship with the corresponding side edge of the center rail 4.There is provided a magnetic gap 9 through which the core 5 is faced tothe edge surface of the center rail 4. And also, a bonding glass 6 isprovided to secure the core 5 to the slider 1.

A winding 7 is wound around a centrally extending vertical columnportion of the core 5.

Details of the connecting structure between the slider 1 and the core 5is enlargedly shown in FIG. 2. As clearly shown in FIG. 2, a magneticgap 9 is provided on an edge surface of the slider 1. The magnetic gap 9is a non-magnetic film made of a non-magnetic material such as SiO₂. Anapplication of the thin film fabrication technology such as sputteringenables this non-magnetic film 9 to grow uniformly on the edge surfaceof the slider 1.

Also shown in FIG. 2 is a magnetic metal film 13 formed on a coresurface 5a that is confronted to the magnetic gap 9. This magnetic metalfilm 13 is made of a magnetic metal material such as Fe--Ni seriesalloy, Fe--Al--Si series alloy, Fe series amorphous, or Co seriesamorphous and the like. And, this magnetic metal film 13 is constructedon the confronting core surface 5a by an application of the thin filmfabrication technology such as sputtering.

As to the characteristic feature of the present invention, the magneticmetal film 13 is formed with a recessed portion 15 that is retractedfrom a medium confronting surface 14 to have a depth t. This recessdepth t is set to 10 nm in this embodiment.

With this arrangement, the magnetic metal film 13 is effectivelyprevented from being directly brought into contact with a magnetic disk11 when the magnetic disk 11 is in a stationary condition without beingturned. In more detail, as there is provided the recessed portion 15that is retracted from the medium confronting surface 14 by the depth t,the magnetic metal film 13 is kept away from lubricant 201 coated on thesurface of the magnetic disk 11 or moisture 202 settled on the surfaceof the magnetic disk 11 so as not to cause chemical reactionirrespective of its chemically active nature. Thus, it becomes possibleto prevent the magnetic metal film 13 from causing color change and soon. Therefore, various characteristics of the magnetic head are maintainproperly without being adversely deteriorated.

Next, a relationship between the depth t of the recessed portion 15 anda relative output of the magnetic head is explained. In this embodiment,the measurement of the relationship between the depth t of the recessedportion 15 and the relative output of the magnetic head is carried outin two cases of lengths 0.5 um and 0.3 um with respect to the magneticgap 9. Furthermore, a flying height of the magnetic head is set to 100nm. And, the size of the magnetic disk is 3.5 inches. Moreover,Co--Ni--Cr is used as a material for the magnetic film. The result ofthis measurement is shown in FIG. 3.

As can be understood from FIG. 3, in each case, the relative outputshows a tendency that it steeply decreases after the depth t exceeds 20nm. Accordingly, it is preferable for the depth t of recessed portion 15to be designed not to exceed 20 nm. Furthermore, by taking account ofthe fact that the thickness of the lubricant coated on the surface ofthe magnetic disk is approximately 2 nm, it is concluded that the deptht of the recessed portion 15 is preferable if it is set within a rangefrom 2 nm to 20 nm. Especially, a superior result is expected when therecess depth t is set within a narrower range from 5 nm to 15 nm.

Next, one method for fabricating the recessed portion 15 on the magneticmetal film 13 is explained hereinafter.

After the magnetic head is completed, this magnetic head is immersed 5to 10 minutes in alkali etchant that can etch the magnetic metal film13. Subsequently, the etchant is sufficiently washed away by flowingwater. Thus, only the magnetic metal film 13 is etched in such a mannerthat the recessed portion 15 is provided at the same side as the mediumconfronting surface 14. The pH of the etchant is desirable in this caseto be 11.sup.˜ 13.

As is described in the foregoing description, the recessed portion 15 isprovided on the magnetic metal film 13 secured on the gap confrontingsurface 5a of the core 5 by forming hollow from the medium confrontingsurface 14. Therefore, the magnetic metal film 13 is prevented fromdirectly contacting with the lubricant coated on the surface of themagnetic disk or the moisture settled on the surface of the magneticdisk. Thus, color change or the like is not caused on the magnetic metalfilm 13 and therefore various characteristics of the magnetic head aremaintained properly without being deteriorated.

SECOND EMBODIMENT

A magnetic head apparatus in accordance with a second embodiment of thepresent invention is perspectively shown in FIG. 4. As shown in FIG. 4,a slider portion 18 has a pair of floating rails 17, 18 elongated inparallel with each other at opposite both ends of the slider portion 18.The slider portion 18 consists of substrates 16a, 16b made of anon-magnetic material such as ceramic and a laminated core 19 beingsandwiched between these substrates 16a, 16b.

Furthermore, the slider portion 18 is formed with a winding groove 16con the edge surface thereof. Cores 20 and 21 are provided along bothvertical edges of one side surface of the slider portion 16. One core20, disposed vertically at left-hand side of the slider portion 16 inFIG. 4, is secured on the edge surface of the slider portion 16 toconfront to the winding groove 16c formed thereon through a non-magneticmaterial serving as the magnetic gap, in such a manner that the outersurface of the core 20 exactly coincides with the outer surface of thefloating rail 18.

In the same manner, the other core 21, disposed vertically at right-handside of the slider portion 16 in FIG. 4, is secured on the edge surfaceof the slider portion 16 to confront to the winding groove 18c formedthereon through a non-magnetic material serving as the magnetic gap, insuch a manner that the outer surface of the core 21 exactly coincideswith the outer surface of the floating rail 17.

As the magnetic head used in this embodiment is a one-track type, thecore 21 is constituted by a non-magnetic material such as a ceramic. Onthe other hand, the core 20 is constituted by the substrates 20a, 20bmade of a non-magnetic material such as ceramic and a laminated core 19sandwiched therebetween.

An area circled by a dashed line and designated by a reference symbol Hin FIG. 4 is enlargedly shown in FIG. 5. In FIG. 5, a reference numeral22 denotes the magnetic gap which is located between the slider portion16 and the core 20. As can be seen in the drawing, the laminated core 19is constituted by alternately laminating a magnetic metal film 19a andan insulation film 19b. Though the laminated core 19 consists of threelayers 19a, 19a, and 19a of the magnetic metal film and two layers 19b,19b of the insulation film, it is needless to say that the number ofthese layers can be increased or decreased as occasion demands.

The magnetic metal film 19a is made of a magnetic metal material such asFe--Ni series alloy, Fe--Al--Si series alloy, Fe series amorphous, or Coseries amorphous and the like. And, the insulation film 19b is made ofan insulation material such as SiO₂. Thus constituted laminated core 19is fabricated in the following manner.

First of all, the magnetic metal film 19a is grown on the substrate 16athrough an application of the thin film fabrication technologyrepresented by sputtering or deposition. And then, the insulation film19b is grown on this magnetic metal film 19a in the same way. Further,by repeating this fabricating cycle, an alternately laminated structureof the magnetic metal film 19a and the insulation film 19b can beconstructed on the substrate 16a.

When the width of the laminated core 19 becomes as thick as apredetermined value; i.e. a track width, the outer substrate 16b isbonded on the laminated core 19 by means of adhesive material 19c suchas bonding glass.

The laminated core 19 provided in the core 20 is also fabricated in thesame fashion.

FIG. 6 is a cross-sectional view taken along a line A-B in FIG. 5. Ascan be seen from FIG. 8, each magnetic metal film 19a is formed with arecessed portion 19d at the same side as a medium confronting surface23. And, in this embodiment, the depth t of the recessed portion 19d isset to 10 nm from the medium confronting surface 23.

By providing the recessed portion 19d on the magnetic metal film 19a inthis manner, the magnetic metal film 19a is surely prevented from beingbrought into contact with the magnetic disk when the magnetic disk is ina stationary condition without being turned. Accordingly, the magneticmetal film 19a cannot cause chemical reaction with the lubricant coatedon the magnetic disk or moisture settled on the surface of the magneticdisk irrespective of the chemically active nature of the magnetic metalfilm 19a. Thus, no color change is generated on the magnetic metalsurface 19a and therefore no deterioration in various characteristics ofthe magnetic head will be expected.

Next, a relationship between the depth t of the recess portion 19d and arelative output of the magnetic head is explained. In this secondembodiment, the measurement of the relationship between the depth t ofthe recess portion 19d and the relative output of the magnetic head iscarried out in two cases of lengths 0.5 μm and 0.3 μm with respect tothe magnetic gap 22. Furthermore, a flying height of the magnetic headis set to 100 nm. And, the size of the magnetic disk is 3.5 inches.Co--Ni--Cr is used as a material for the magnetic film. The result ofthis measurement is shown in FIG. 7.

As can be understood from FIG. 7, in each case, the relative outputshows a tendency that it steeply decreases after the depth t exceeds 20nm. Accordingly, it is preferable for the depth t of the recessedportion 19d to be designed not to exceed 20 nm. Furthermore, by takingaccount of the fact that the thickness of the lubricant being coated onthe surface of the magnetic disk is approximately 2 nm, it is concludedthat the depth t of the recessed portion 19d is preferable to be setwithin a range from 2 nm to 20 nm. Furthermore, a superior result isexpected if the recess depth t is set within a narrower range from 5 nmto 15 nm.

Next, one method for fabricating the recessed portion 19d on themagnetic metal film 19a is explained hereinafter.

After the manufacturing of the magnetic head is completed, the magnetichead is immersed 5 to 10 minutes in alkali etchant that is effective toetch the magnetic metal film 19a and noneffective against the substrate.Subsequently, the etchant is sufficiently washed away by flowing water.Thus, the magnetic metal film 19a is only etched in such a manner thatthe recessed portion 19d is provided on the magnetic metal film 19a atthe same side as the medium confronting surface 23. The pH of theetchant is desirable in this case to be 11.sup.˜ 13.

FIG. 8 shows a modified embodiment of the second embodiment. In FIG. 8,almost all the components such as substrates 16a, 16b, laminated core19, magnetic metal films 19a, insulation films 19b, and adhesivematerial 19c have substantially the same structures as those shown inFIG. In this embodiment, a recessed portion 19e has a depth t from themedium confronting surface 23. However, this recessed portion 19e isdifferent from the recessed portion 19d of FIG. 6 in that it is formedwidely to range from edge to edge of the laminated core 19. Even if therecessed portion is fabricated in this manner, substantially the sameeffect as the second embodiment can be obtained. It is preferable todesign the depth t to be within a range from 2 nm to 20 nm, too.

THIRD EMBODIMENT

A magnetic head apparatus in accordance with a third embodiment of thepresent invention is perspectively shown in FIG. 9. In FIG. 9, a slider24 is made of a non-magnetic material such as a ceramic and has a pairof floating rails 25, 28 elongated in parallel with each other atopposite both ends of the slider 24.

These floating rails 25, 28 have end surfaces being attached withthin-film type magnetic heads 27, 28, respectively. The thin-film typemagnetic head 27 is provided with two leads 29, 30 for supplying currentto coil layer and discharging it from the coil layer. In the same way,the thin-film type magnetic head 28 is provided with two leads 31, 32.

FIG. 10 is an enlarged perspective diagram showing the thin-film typemagnetic heat 27. In FIG. 10, a reference numeral 33 denotes the coillayer of spiral-shaped that is constituted by a conductive material suchas copper. The coil layer 33 has a pair of edge portions 34, 35. Oneedge portion 35 is connected to the lead 29, and the other edge portion34 is connected to the lead 30. There is provided an upper magneticlayer 36 on the coil layer 33. The thin-film type magnetic head isfurther explained in detail with reference to FIG. 11.

FIG. 11 is a cross-sectional view taken along a line E-F of FIG. 10.First of all, on the slider 24 that serves as a substrate as well as aslider, there is provided an insulation layer 37 being formed by aninsulation material such as SiO₂. Then, a lower magnetic layer 38 isconstructed on this insulation layer 37 through an application of thethin layer fabricating technology. In turn, on this lower magnetic layer38, there is formed a gap layer 39 which is made of a non-magneticmaterial such as SiO₂. This gap layer 39 serves as a magnetic gap.Subsequently, a coil layer 33 is formed on this gap layer 39.

The coil layer is provided in such a manner that a conductive film isuniformly formed, first of all, on the gap layer 39 through anapplication of the thin-film fabrication technology such as a depositionand, thereafter, the conductive film is lifted off in a spiral shape toremain a coil layer 33 on the gap layer 39.

Then, the coil layer 33 is covered by an insulation layer 40 being madeof an insulation material such as photoresist. Further, on thisinsulation layer 40, there is provided the upper magnetic layer 36 so asto constitute a magnetic circuit together with the lower magnetic layer38. Moreover, a protection layer 41 is formed so as to cover the uppermagnetic layer 36 and the coil layer 33 protruding from the uppermagnetic layer 36. This protection layer 41 is also formed through anapplication of the thin-film fabrication technology such as sputtering.And, the material for the protection layer 41 is generally selected frommaterials having good weatherability such as SiO₂.

In thus formed thin-film type magnetic head, the upper magnetic layer 36and the lower magnetic layer 38 are made of a magnetic metal material.For example, Fe--Ni series alloy, Fe--Al--Si series alloy, Fe seriesamorphous, and Co series amorphous can be used as a material for theupper magnetic layer 36. The lower magnetic layer 38 can be constitutedby the same material as the upper magnetic layer 36.

As to the characteristic feature of the present invention, recessedportions 43, 44 are formed on the upper and lower magnetic layer 38, 38,respectively. Both the recessed portions 43, 44 are provided at the sameside as a medium confronting surface 42 and have a depth t from themedium confronting surface 42. In this embodiment, this depth t is setto 10 nm.

By providing the recessed portions 43, 44 on the upper and lowermagnetic layers 38, 38 in this manner, the upper and lower magneticlayers 38, 38 are surely prevented from being brought into contact withthe magnetic disk when the magnetic disk is in a stationary conditionwithout being turned. Accordingly, the upper and lower magnetic layers38, 38 cannot cause chemical reaction with the lubricant coated on themagnetic disk or moisture settled on the surface of the magnetic diskirrespective of the chemically active nature of magnetic metal materialconstituting the upper and lower magnetic layers 38, 38. Thus, no colorchange is generated on the upper and lower magnetic layers 38, 38 andtherefore no deterioration in various characteristics of the magnetichead will be expected.

Next, a relationship between the depth t of the recessed portions 43, 44and a relative output of the magnetic head is explained. In this thirdembodiment, the measurement of the relationship between the depth t ofthe recessed portions 43, 44 and the relative output of the magnetichead is carried out in two cases of lengths 0.5 μm and 0.3 μm withrespect to the gap layer 39. Furthermore, a flying height of themagnetic head is set to 100 nm. And, the size of the magnetic disk is3.5 inches. Co--Ni--Cr is used as a material for the magnetic film. Theresult of this measurement is shown in FIG. 12.

As can be understood from FIG. 12, in each case, the relative outputshows a tendency that it steeply decreases after the depth t exceeds 20nm. Accordingly, it is preferable for the depth t of the recessedportions 43, 44 to be designed not to exceed 20 nm. Furthermore, bytaking account of the fact that the thickness of the lubricant beingcoated on the surface of the magnetic disk is approximately 2 nm, it isconcluded that the depth t of the recessed portions 43, 44 is preferableif it is set within a range from 2 nm to 20 nm. Furthermore, a superiorresult is expected when the recessed depth t is set within a narrowerrange from 5 nm to 15 nm.

Next, one method for fabricating the recessed portions 43, 44 on theupper and lower magnetic layers 36, 38 explained hereinafter.

After the manufacturing of the magnetic head is completed, the magnetichead is immersed 5 to 10 minutes alkali etchant that is effective toetch the upper and lower magnetic layers 36, 38 and noneffective againstthe substrate. Subsequently, the etchant is sufficiently washed away byflowing water. Thus, the upper and lower magnetic layers 36, 38 are onlyetched in such a manner that the recessed portions 43, 44 are formed onthe upper and lower magnetic layers 36, 38 at the same side as themedium confronting surface 42. The pH of the etchant is desirable inthis case to be 11.sup.˜ 13.

FOURTH EMBODIMENT

A magnetic head apparatus in accordance with a fourth embodiment of thepresent invention is shown in FIG. 13. In FIG. 13, a reference numeral45 denotes an I-shaped core made of a magnetic oxide material such asferrite. The core 45 has one side surface 45a being confronted to amagnetic gap 50. A magnetic metal film 48 is formed on this gapconfronting surface 45a. The magnetic metal film 48 is made of amagnetic metal material. For example, Fe--Ni series alloy, Fe--Al--Siseries alloy, Fe series amorphous, and Co series amorphous can be usedas a material for the magnetic metal film 46.

Furthermore, the magnetic metal film 46 is constructed through thethin-film fabrication technology such as sputtering or metal plating andthe like.

A reference numeral 47 denotes a C-shaped core that is made of amagnetic oxide material such as ferrite. The core 47 has side surfaces47a being confronted to the magnetic gap 50. Magnetic metal films 48 areformed on these gap confronting surfaces 47a. This magnetic metal film48 is made of the same material as the magnetic metal film 46 throughthe same fabrication method as the magnetic metal film 46.

Furthermore, the winding groove 49 is formed in the core 47 to opentoward the magnetic gap 50. Cores 45 and 47 are connected by means ofbonding glass 51 in such a manner that the magnetic metal film 46 andthe magnetic metal film 48 confront each other to sandwich the magneticgap 50 made of a non-magnetic film material therebetween.

Moreover, as to the characteristic feature of the invention, recessedportions 53, 54 are provided on the magnetic metal films 46, 48,respectively. Both the recessed portions 53, 54 are formed at the sameside as a medium confronting surface 52 and have a depth t from themedium confronting surface 52. In this embodiment, this depth t is setto 10 nm.

By providing the recessed portions 53, 54 on the magnetic metal films46, 48 in this manner, the magnetic metal films 46, 48 are surelyprevented from being brought into contact with the magnetic disk whenthe magnetic disk is in a stationary condition without being turned.Accordingly, the magnetic metal films 46, 48 cannot cause chemicalreaction with the lubricant coated on the magnetic disk or moisturesettled on the surface of the magnetic disk irrespective of thechemically active nature of magnetic metal material constituting themagnetic metal films 46, 48.

A relationship between the depth t of the recessed portions 53, 54 andits relative output of the magnetic head is substantially the same asthat shown in FIG. 3. Namely, the relative output shows a tendency thatit steeply decreases after the depth t exceeds 20 nm. Accordingly, it ispreferable for the depth t of the recessed portions 53, 54 to bedesigned not to exceed 20 nm. Furthermore, by taking account of the factthat the thickness of the lubricant being coated on the surface of themagnetic disk is approximately 2 nm, it is concluded that the depth t ofthe recessed portions 53, 54 is preferable if it is set within a rangefrom 2 nm to 20 nm. Furthermore, a superior result is expected when therecessed depth t is set within a narrower range from 5 nm to 15 nm.

Next, one method for fabricating the recessed portions 53, 54 on themagnetic metal films 46, 48 is explained hereinafter.

After the manufacturing of the magnetic head is completed, the magnetichead is immersed 5 to 10 minutes in alkali etchant that is effective toetch the magnetic metal films 46, 48 and noneffective against thesubstrate. Subsequently, the etchant is sufficiently washed away byflowing water. Thus, the magnetic metal films 46, 48 are only etched insuch a manner that the recessed portions 53, 54 are formed on themagnetic metal films 46, 48 at the same side as the medium confrontingsurface 52. The pH of the etchant is desirable in this case to be11.sup.˜ 13.

As is described in the foregoing description, the recessed portion isprovided only on the component made of a magnetic metal material byforming hollow from the medium confronting surface. Therefore, themagnetic metal component is surely prevented from being brought intocontact with the lubricant directly coated on the surface of themagnetic disk or the moisture settled on the surface of the magneticdisk. Thus, color change or the like is not caused on the magnetic metalcomponent and therefore various characteristics of the magnetic head aremaintained properly without being deteriorated.

As this invention may be embodied in several forms without departingfrom the spirit of essential characteristics thereof, the presentembodiments are therefore illustrative and not restrictive, since thescope of the invention is defined by the appending claims rather than bythe description preceding them, and all changes that fall within meetsand bounds of the claims, or equivalence of such meets and bounds aretherefore intended to embraced by the claims.

What is claimed is:
 1. A magnetic head apparatus comprising:first andsecond cores made of a magnetic oxide material and constituting part ofa magnetic head; a winding groove provided on at least one of said firstand second cores; a magnetic gap provided between said first and secondcores; a first magnetic metal film interposed between said first coreand said magnetic gap; a second magnetic metal film interposed betweensaid second core and said magnetic gap; a medium confronting surface onone side of said magnetic head which is brought into slidable contactwith a surface of a medium; said first and second magnetic metal filmhaving a surface confronting the surface of the medium; and said surfaceof each said first and second magnetic films being recessed from saidmedium confronting surface, to form a recessed portion wherein aclearance between the surface of said medium at the center of saidrecessed portion is larger than a clearance at the edge of said recessedportion and wholly spaced from said medium confronting surface whilesaid magnetic gap is brought into contact with said medium confrontingsurface.
 2. A magnetic head apparatus in accordance with claim 1 inwhich a depth of said recessed surface of the magnetic metal film issmaller than a predetermined value corresponding to a point where asteep attenuation occurs in a relative output of the magnetic head inrelation to the depth of said recessed surface.
 3. A magnetic headapparatus in accordance with claim 2 in which the depth of said recessedsurface of the magnetic metal material is larger than a value equivalentto a thickness of lubricant coated on the surface of said medium.
 4. Amagnetic head apparatus in accordance with claim 1 in which saidrecessed surface of the magnetic metal film is retracted from the mediumconfronting surface by 2 nm to 20 nm.
 5. A magnetic head apparatus inaccordance with claim 1 in which said recessed surface of the magneticmetal material is retracted from the medium confronting surface by 5 nmto 15 nm.
 6. A magnetic head apparatus in accordance with claim 1 inwhich said recessed surface of the magnetic metal film is fabricated insuch a manner, after a manufacturing of the magnetic head is completed,this magnetic head is immersed 5 to 10 minutes in alkali etchant so thatonly the magnetic metal film is etched, and subsequently, the etchant issufficiently washed away by flowing water, whereby producing therecessed surface at the same side as the medium confronting surface. 7.A magnetic head apparatus in accordance with claim 6 in which saidetchant has a pH of 11.sup.˜
 13. 8. A magnetic head apparatus inaccordance with claim 1 in which said core is made of ferrite and saidmagnetic metal film is made of at least one material belonging to agroup consisting of Fe--Ni series alloy, Fe--Al--Si series alloy, Feseries amorphous, and Co series amorphous.